The Stem Cell Biology Program includes nine Washington University faculty members. Program members study the biology of hematopoietic stem cells in health and disease. The mechanisms of stem cell mobilization are under investigation, since the application of this knowledge may improve the ability to obtain pure, high quality stem cells for transplantation. Stem cells and/or early hematopoietic progenitors are genetically altered in many bone marrow disease states, and in acute and chronic myelogenous leukemias. Program members currently are developing novel transgenic targeting systems to express a variety of potentially leukemogenic cDNAs into specific early hematopoietic compartments, including stem cells. Program members are evaluating the mechanisms by which cytotoxic lymphocytes kill leukemic hematopoietic progenitors, and whether grant vs. leukemia effects can be separated from graft vs. host effects. Finally, hematopoietic stem cells are an attractive target for gene transfer protocols. Program members are developing novel strategies for transducing these cells with a variety of viral vectors in disease model systems. The Stem Cell Biology Program will interact closely with the Leukemia/Lymphoma/Transplant Focus Group to ensure that basic information obtained from this Program will have the opportunity to be translated into human studies. The studies being conducted by Program members have a wide variety of potential applications for patients with cancer.